This invention relates to alarm systems for liquid containing vessels. More particularly, this invention relates to alarm systems sensing the leakage of corrosive fluids into the space between a liner and the outer steel walls of a corrosive liquid containing tank.
Tanks for the confinement of corrosive solutions such as acid are typically fabricated of steel with a non corroding liner inside, normally made from lead. Such tanks find use in metal plating operations and other chemical cleaning applications. Upon the occurrence of a break or fracture in the lead lining of a tank, the corrosive liquid solution passes into the space between the lead lining and the outer steel walls of the tank. There it will collect and corrode away the outer wall of the steel tank. This seriously damages the structural integrity of the tank and will eventually cause other damage when the corrosive solution finally breaks through the outer walls and drains onto flooring or other objects in the vicinity of the tank. Also, serious environmental consequences can result if a hazardous corrosive substance such as a contaminated acid bath enters into a municipal sewage system without proper treatment.
If the leakage from the liner continues to any great extent, the entire tank assembly usually must be replaced. In some instances the steel tank can be repaired by a patch plate; however, all of the lead lining must be removed and replaced if such is to be done. Such repairs or replacement are quite expensive. It is therefore an object to provide for an early means of detecting failures in the liners to such corrosive liquid containing tanks before the damage to the steel outer tank reaches an irreversible stage.